public class Client {
    public static void main(String[] args) {
        Bird eagle = new Eagle();
        Bird pengun = new Penguin();

        eagle.display();
        eagle.performFly();
        eagle.performSwim();

        pengun.display();
        pengun.performFly();
        pengun.performSwim();

        pengun.setSwimBehavior(new UnableSwim());
        pengun.performSwim();
    }
}